Deer looks at oncoming car - headlights.

Auto-deer accidents cause about 150 deaths and $1.1 billion in property damage each year in the U.S., according to the National Highway Traffic Safety Administration. An adult male deer can weigh up to 300 pounds, and can seemingly leap out of nowhere onto the road in an instant.

As fall and early winter arrive, deer are even more numerous because the animals are in spawning mode and are thus less likely to pay attention to traffic as they pursue romantic hook-ups. About two-thirds of deer collisions occur during this period, authorities say, with most of the collisions happening in the two hours prior to sunrise and after sunset.

Officials have experimented with many deer-control methods nationwide, such as strategically placed fences. Authorities say better reporting of deer collisions would help address the problem and it also would be useful if the precise locations of the collisions were recorded to identify problem areas. But most motorists don’t call the police after striking a deer unless their cars are disabled.

One of the most popular, but least effective methods of warning drivers are “deer crossing” signs. The signs are up all through the year and regular travelers tend to ignore them over time. Another ineffective method of keeping vehicles and deer away from each other are commercial deer whistles, which attach to cars and are designed to scare the animals away. The whistles produce ultrasonic noise at car speeds over 30 mph. Studies have shown, however, that these devices have no effect.

And if it seems there are more deer near highways now than there were years ago, that’s correct. One study reported an American deer population of 500,000 in 1908; today there are 30 million or more, and that number increases every year. It’s possible, though, to minimize the chances that a motorist will meet up face-to-face with one of the mild-mannered leaf-munchers on the highway. Here’s a list of deer-related traffic tips:

- Research has shown that a driver’s best defense is to drive responsibly. Drive at a safe speed or, at the very least, don’t speed when driving through forested areas. Always wear a seat belt and insist passengers wear them, too.

- Keep an eye on vehicles up ahead. If their brake lights suddenly come on, there might be a deer (or a herd) near or on the highway.

- Be especially aware at dusk and dawn. This is typically when deer herds are heaviest by the sides of roads and it’s also a time of day when it’s neither completely light nor dark, so it’s harder for humans to see.

- Drive defensively. Be ready to take evasive action. If a deer appears on the highway, step hard on either the gas or the brake pedal. Flooring the throttle to pass a deer and its herd might net a speeding ticket, but it will help avoid what could be a fatal collision.

- Use the high beams where possible. Putting on the “brights” will help illuminate the eyes of animals so they can be seen sooner. Also, flash the high beams to warn approaching drivers when deer are spotted on or near the highway.

- Blowing horns and flashing the headlights can alarm deer and cause them to run straight toward the highway.